Light emitting device and method of manufacturing the same

ABSTRACT

To provide a light emitting device capable of promoting an efficiency of taking out light to outside and achieving highly reliable bright image display by lower power consumption, in a light emitting device including a plurality of pixels and including a transistor and a pixel electrode electrically connected to the transistor at each of the plurality of pixels, an insulating film provided below the pixel electrode includes an opening portion an side surface of which is a curved face at a light emitting region. Light emitted from a light emitting element is focused by the curved face provided at the insulating film to reduce propagation thereof in a lateral direction, the efficiency of taking out the light is promoted and therefore, bright image display can be achieved without particularly increasing a current amount to be injected.

FIELD OF THE INVENTION

The present invention relates to a technical field of an active matrixtype light-emitting device using electric field-effect type transistors.This invention especially relates to a technical field with respect to alight emitting display device in which thin film transistors areprovided in a plurality of pixels respectively.

DESCRIPTION OF THE RELATED ART

In recent years, the development of a light emitting display device inwhich thin film transistors (TFTs) are integrated over a glass substratehas been progressed. Especially, an active matrix type light emittingdisplay device in which transistors are provided in respective pixels issuitable for reproduction of moving pictures because of its highresponse speed. Therefore, the product development of the active matrixtype light emitting display device has been hurried for future diffusionof digital contents. However, low reliability is cited as the biggestproblem in productization of the light emitting display device.

A light emitting material (mainly, an organic compound) that is used tothe light emitting display device emits light by flowing a trace amountof electric current. However, the light emitting material has defects ofserious deterioration and shorter lifetime. The probability ofdeterioration of the light emitting material is increased when theamount of flowing electric current is increased. On the other hand,luminance of the light emitting material is decreased when the amount offlowing electric current is reduced. That is, the light emitting displaydevice has a relationship of trade-off between bright image display andhigh reliability.

Ultimately, the bright image display with few amount of electric currentdepends on how the generated light can be taken out outside toeffectively. Conventionally, a low inner quantum efficiency and the likecaused by characteristics of the light emitting material itself has beena problem. However, improvement in this field has been advanced by thedevelopment of phosphorescent light emitting materials and the like of atriplet exciton. As result, the most desired improvement at present is alow efficiency of taking out the generated light to outside of 20%,therefore light loss due to the inner reflection in a multi-layered filmand a substrate surface has been a problem.

SUMMARY OF THE INVENTION

In view of the aforementioned problems, an object of the presentinvention is to provide a technique to improve the efficiency of takingout the generated light without increasing the number of process.Furthermore, another object of the present invention is to achievebright image display with low power consumption by promoting theefficiency of light and provide a light emitting device capable ofdisplaying bright image without deteriorating reliability.

The invention is a light emitting device including a plurality of pixelsand including a transistor and a pixel electrode electrically connectedto the transistor at each of the plurality of pixels, wherein aninsulating film provided below the pixel electrode includes an openingportion a side surface of which is a curved face in a light emittingregion. The opening portion indicates an opening portion formed at theinsulating film provided below the pixel electrode formed by means ofetching or the like. That is, the invention is characterized in that inthe light emitting region (refers to a region capable of opticallyrecognizing light in a pixel), by providing the opening portion the sidesurface of which is the curved face at the insulating film below thepixel electrode and forming the pixel electrode to cover the openingportion, undulations (recesses and projections) along the shape of theopening portion are provided to the pixel electrode. Therefore, asurface of the pixel electrode is provided with the curved face alongthe shape of the opening portion.

The gist and the effect of the invention will be explained in referenceto FIG. 1. In FIG. 1, numeral 101 designates an insulating film, numeral102 designates an opening portion provided at the insulating film 101,numeral 103 designates a pixel electrode, numeral 104 designates a lightemitting layer and numeral 105 designates an opposed electrode. Althoughas the insulating film 101, it is preferable to use a photosensitiveresin film of a photosensitive acrylic resin film, a photosensitivepolyimide film or the like such that the side surface of the openingportion 102 can be constituted by the curved face, a material other thanthe photosensitive resin film may be used so far as the side surface ofthe opening portion 102 can be constituted by the curved face byadjusting etching conditions. Further, the photosensitive resin film isordinarily colored in light brown color and therefore, it is necessaryto make the photosensitive resin film transparent to visible light bysubjecting the photosensitive resin film to decoloring treatment(bleaching treatment). In the decoloring treatment, light (typicallyultraviolet ray) used in exposure may be irradiated to a total of apattern after development.

Further, the opening portion 102 indicates a portion of the insulatingfilm 101 at which a thickness of the insulating film 101 is increasingcentering on a portion thereof constituting a recess shape by removingthe insulating film 101 with a radius of curvature. The radius ofcurvature needs not to be always constant but may be changedcontinuously or in steps. For example, in the case of the photosensitiveresin film, the side surface of the opening portion becomes the curvedface necessarily by exposure and development and the opening portionwhich constitutes the invention naturally includes also the openingportion formed in this way. Further, the shape of the opening portion isnot particularly limited but may be constituted by a groove shape, acircular shape, a lattice shape or other geometrical shape and aposition for forming the opening portion may be regular or may beirregular.

The pixel electrode 103 is an electrode comprising a conductive film fortransmitting visible light and typically, an oxide conductive film ofindium oxide, tin oxide, a compound of tin oxide and zinc oxide, acompound of indium oxide and zinc oxide or the like can be usedtherefor. Or, the pixel electrode 103 may be constituted by a laminatedbody of a metal film having a thickness capable of transmitting visiblelight (typically, a thickness equal to or smaller than 100 nm) and anoxide conductive film. Since the pixel electrode 103 is provided overthe insulating film 101 provided with the opening portion 102, the pixelelectrode 103 covers the opening portion 102 as shown by FIG. 1, as aresult, the surface of the pixel electrode 103 is provided with a curvedface along the shape of the opening portion.

Further, the light emitting layer 104 is a laminated body constituted bylaminating a light emitting layer, a carrier injecting layer, a carriertransporting layer, a carrier hampering layer and other organic compoundor inorganic compound necessary for luminescence. Any publicly-knownconstitution may be used for a constitution of the light emitting layer104. Further, an element provided with a light emitting layer between apair of electrodes (in this case, the pixel electrode 103 and theopposed electrode 105) is referred to as a light emitting element. Oneof the pair of electrodes is referred to as anode and other thereof isreferred to as cathode. The anode is an electrode on a side of injectinga hole and therefore, a material having a comparatively high workfunction is used and the cathode is a electrode on a side of injectingan electron and therefore, a material having a comparatively low workfunction is used. In the case of FIG. 1, when an oxide conductive filmis used for the pixel electrode 103, the pixel electrode 103 becomes theanode and when a metal film including an element belonging to group 1 orgroup 2 of the periodic table is used for the opposed electrode 105, theopposed electrode 105 becomes the cathode.

The technical thought of the invention will be explained here. Whenvoltage is applied between the pixel electrode 103 and the opposedelectrode 105, holes and electrons are injected to the light emittinglayer 104 and recombined at inside of the light emitting layer 104 andlight is emitted. Although generated light advances radially, the mostportion thereof transmits through the pixel electrode 103 fortransmitting visible light and is optically recognized. In FIG. 1, bothof light directly transmitting therethrough and light reflected by theopposed electrode 105 are described as normal light. Further, there ispresent light propagating at inside of the light emitting layer 104 bybeing randomly reflected in a film face direction in the generated lightand in the related art, the propagated light is propagated to an end ofa substrate and is light which cannot be taken out. However, byembodying the invention, all of the pixel electrode 103, the lightemitting layer 104 and the opposed electrode 105 are provided with thecurved faces and therefore, the propagated light in the film facedirection can be directed to a lower side to take out, as a result, anamount of light which can be optically recognized is increased more thanthat in the structure of the prior art. That is, brightness of displaycan be increased.

As described above, the invention is characterized in constructing aconstitution in which the structure per se of the light emitting elementis provided with a radius of curvature by providing the opening portionthe side surface of which is the curved face at the insulating film andthe propagated light which is propagated over a plurality of pixels inthe related art can be made to stay at individual pixels to take out andas an effect thereof, by efficiently taking out the propagated lightpropagated in the film face direction of the light emitting layer, thebrightness in the light emitting region can be increased withoutincreasing power consumption (that is, without deterioratingreliability). Further, the opening portion may be formed when a contacthole is formed at the insulating film and therefore, it is notparticularly necessary to increase the number of steps in forming theopening portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view of the basic principle of the invention;

FIGS. 2A and 2B are a top view of a pixel and a circuit diagram of alight emitting device;

FIGS. 3A to 3C are sectional views of the pixel of the light emittingdevice;

FIGS. 4A and 4B are sectional views of the pixel of the light emittingdevice;

FIGS. 5A and 5B are a top view of a pixel and a circuit diagram of alight emitting device;

FIGS. 6A and 6B are sectional views of the pixel of the light emittingdevice;

FIGS. 7A and 7B are a top view of a pixel and a circuit diagram of alight emitting device;

FIGS. 8A and 8B are sectional views of the pixel of the light emittingdevice;

FIGS. 9A to 9C are sectional views of a pixel of a light emittingdevice;

FIGS. 10A and 10B are sectional views of a portion of a pixel of a lightemitting device;

FIGS. 11A to 11D are views constituting an outlook of a light emittingdevice; and

FIGS. 12A to 12H are views showing specific examples of electricapparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[Embodiment 1]

The embodiment is an example of a light emitting display device of theinvention. In FIGS. 2A and 2B, FIG. 2A is a top view of a pixel of thelight emitting display device (however, up to forming a pixel electrode)and FIG. 2B is a circuit diagram thereof. Further, drawings incorrespondence with sectional views provided by cutting FIG. 2A alonglines A-A′, B-B′ and C-C′ are respectively FIGS. 3A through 3C.

As shown by FIGS. 2A and 2B, a pixel portion of the light emittingdisplay device is provided with a plurality of pixels surrounded by agate wiring 11, a data wiring 12 and a power source wiring (wiring forsupplying constant voltage or constant current)13 in a matrixarrangement and each pixel is provided with a thin film transistor(hereinafter, referred to as switching TFT) 14 functioning as aswitching element, TFT (hereinafter, referred to as driving TFT) 15functioning as means for supplying current or voltage for making a lightemitting element emit light, a capacitor portion 16 and a light emittingelement 17. The light emitting element 17 can be formed by providing alight emitting layer over a pixel electrode 18, although not illustratedhere. Further, an opening portion 19 which is a characteristic of theinvention is indicated by a dotted line since the opening portion 19 isprovided below the pixel electrode 18.

Further, although according to the embodiment, an n-channel type TFThaving a multigate structure is used as the switching TFT 14 and aP-channel type TFT is used as the driving TFT 15, a pixel constitutionof a light emitting device needs not to limit thereto and the inventionis applical to any publicly-known constitution.

The n-channel type TFT 14 and the capacitor portion 16 appear in thesectional view of FIG. 3A. Numeral 101 designates a substrate and aglass substrate, a ceramic substrate, a quarts substrate, a siliconsubstrate or a plastic substrate (including a plastic film) can be usedtherefor. Further, numeral 102 designates a silicon nitroxide film,numeral 103 designates a silicon oxynitride film and the films arelaminated to function as a matrix film. Naturally, it is not necessaryto limit to these materials. Further, an activation layer of then-channel type TFT 14 is provided over the silicon oxynitride film 103and the activation layer includes a source region 104, a drain region105, LDD regions 106 a through 106 d, and channel forming regions 107 a,107 b and the two channel forming regions and four LDD regions areprovided between the source region 104 and the drain region 105.

Further, the activation layer of the n-channel type TFT 14 is covered bya gate insulating film 108 over which gate electrodes 109 a and 109 band gate electrodes 110 a and 110 b are provided. Although a siliconoxynitride film is used according to the embodiment as the gateinsulating film 108, when a nitride insulating film, mentioned above, ofan aluminum nitride film or the like having a high specific inductivecapacity is used, an occupied area of the element can be reduced andtherefore, the film is effective in promoting an integration degree.

Further, as the gate electrodes 109 a and 110 a, tantalum nitride filmsare used and as the gate electrodes 109 b and 110 b, tungsten films areused. Such a structure can be constituted by selecting an etchingcondition since these metal films are provided with high selectionratios to each other. With regards to the etching condition,JP-A-2001-313397 by the applicant may be referred to.

Further, a silicon nitride film or a silicon nitroxide film is providedas an insulating film 111 for covering the gate electrodes and aphotosensitive resin film is provided thereover as a flattening film112. Although according to the embodiment, a positive typephotosensitive acrylic resin film is used as the flattening film, anegative type photosensitive acrylic resin film or a positive typephotosensitive polyimide film may be used therefor.

In this case, first contact portions are provided at a laminated bodycomprising the gate insulating film 108 and the insulating layer 111over the source region 104 and over the drain region 105 and theflattening film 112 is provided with second contact portions to containthe first contact portions at inside thereof. For such structure, theremay be selected either method of (1) a method of previously forming thefirst contact portion and thereafter, embedding the first contactportion temporally by the flattening layer and further forming thesecond contact portion and (2) a method of providing the flatteninglayer and thereafter forming the second contact portion and thereafter,forming the first contact portion at inside of the second contactportion by using a new mask. However, although it is preferable to use adry etching method for forming the first contact portion, it ispreferable to avoid the flattening film 112 from being exposed to plasmaand the method of (1) may be regarded as preferable in that meaning.

Further, at this occasion, simultaneous with forming the second contactportion provided at the flattening film 112, the opening portion whichis the characteristic of the invention is formed at the light emittingregion. That is, it is not necessary to particularly increase a processin forming the opening portion for providing a curved face at the pixelelectrode. Naturally, in forming the first contact portion, the lightemitting region may be covered by a resist mask or the like. It is anobject of forming the opening portion to provide the curved face on thesurface of the pixel electrode and therefore, when the opening portionis formed only at the flattening film 112, it is sufficient for theobject.

Further, the data wiring 12 and a connection wiring (corresponding to adrain electrode) 113 are connected to the source region 104 or the drainregion 105 via the first opening portion and the second opening portion.The connection wiring 113 is a wiring connected to the gate of thedriving TFT 15. A structure of interposing a wiring whose majorcomponent is a metal having low resistance such as aluminum or copper byother metal films or a film of an alloy of these metals may be used forthe data wiring 12 and the connection wiring 113.

Further, numeral 114 designates a source region of the driving TFT 15which is connected with the power source wiring 13. Further, the powersource wiring 13 is opposed to a gate wiring 115 of the driving TFT 15via the insulating layer 111 and forms a storage capacitor 16 a.Further, the gate wiring 115 is opposed to a semiconductor film 116 viathe gate insulating film 108 and forms a storage capacitor 16 b. Sincethe power source wiring 13 is connected to a semiconductor film 117, thesemiconductor film 116 functions as an electrode by being supplied withelectric charge therefrom. Since the capacitor portion 16 is constructedby a constitution of connecting the storage capacitors 16 a and 16 b inparallel in this way, large capacitance is provided by a very smallarea. Further, a silicon nitride film having a high specific inductivecapacity is used particularly for the storage capacitor 16 a as adielectric body and therefore, large capacitance can be ensured.

When the first opening portion and the second opening portion, mentionedabove, are formed, although the number of masks used in photolithographysteps is increased compared with that of the related art, by converselyutilizing the increase in the number of masks, as shown by theembodiment, the storage capacitor is newly formed. The point is also oneof characteristics of the invention. The characteristic sufficientlycompensates for the disadvantage of the increase in the masks, as aresult, significantly contributes to development of industry. Forexample, in order to achieve highly fine image display, it is necessaryto promote an aperture rate by reducing an occupied area of the storagecapacitor relative to an area of each element in a display portion andfor that purpose, an increase in the storage capacitor is extremelyuseful.

Further, in FIG. 3B, numeral 118 designates a drain region of thedriving TFT 15 which is connected to a drain electrode 119. Further, thedrain electrode 119 is connected to the pixel electrode 18 to constitutethe pixel. Although according to the embodiment, an oxide conductivefilm (representatively, ITO film) which is transparent to visible lightis used as the pixel electrode 18, the film is not limited thereto.Further, by forming the pixel electrode 18 after forming the drainelectrode 119, there is constructed a constitution in which the pixelelectrode 18 is connected to be brought into contact with an upper faceof the drain electrode 119. At this occasion, as shown by FIG. 3B, theopening portion 19 is recognized at the flattening film 112. A sidesurface of the opening portion 19 is constituted by a curved face andalso a surface of the pixel electrode 18 is constituted by a curved facetherealong.

Next, FIGS. 4A and 14B are drawings respectively in correspondence withFIGS. 3B and 3C, showing a state of finishing the light emitting displaydevice. After providing the pixel electrode 18, an insulating film 121for partitioning the light emitting region is provided. Although theinsulating film 121 may be an inorganic insulating film or a resin film,it is regarded to be preferable to form the insulating film 121 by amaterial the same as that of the flattening film 112 in view of reducingfabrication cost. According to the embodiment, a positive typephotosensitive acrylic resin film is used therefor similar to theflattening film 112.

When the insulating film 121 is provided, a light emitting layer 122, anopposed electrode 123 and a protective film 124 are successively formedthereover. It is preferable to continuously form these films withoutexposing to the atmosphere since adsorption of oxygen or moisturecausing a deterioration can be prevented. Although as the light emittinglayer 122, any publicly-known material and structure may be used,according to the embodiment, as the pixel electrode, an oxide conductivefilm functioning as anode is used and therefore, it is preferable toprovide a hole injecting layer or a hole transporting layer at alowermost layer (layer in contact with the pixel electrode) thereof.Further, conversely, as the opposed electrode 123, a metal filmincluding an element belonging to group 1 or group 2 of the periodictable may be provided to function as a cathode. According to theembodiment, a film of an alloy of aluminum and lithium is used.

The protective film 124 is preferably provided with barrier performancesufficient for preventing invasion of oxygen and moisture from outsideand an insulating film as dense as possible may be used therefor.Further, since the protective film 124 is provided after providing thelight emitting layer 122, it is necessary to adopt a film forming methodcapable for forming a film at room temperature such as a sputteringmethod in consideration of heat resistance of the light emitting layer122. Although according to the embodiment, a silicon nitride film isprovided by a sputtering method, it is not necessary to limit thereto.Further, it is not necessary to constitute the protective film 124 by asingle layer but may be constituted by a laminated layer.

According to the light emitting display device having theabove-described constitution, as shown by FIGS. 4A and 4B, light isirradiated to a side of the substrate 101 and as explained in referenceto FIG. 1, the curved face derived from the opening portion provided atthe flattening film 112 serves as a focusing lens, an efficiency ofcollecting light to a side of the light emitting region is promoted andbrightness is increased. A direction of light is as shown by an arrowmark and in addition to light capable of being directly recognizedoptically as in the related art, light emitted from a portion of thepixel electrode 18 having the curved face (including propagated light)is present.

As described above, by embodying the invention by the constitution shownin the embodiment, the surface of the pixel electrode 18 can beconstituted by the curved face at the light emitting region in the pixel(which may be referred to as a region partitioned by the insulating film121 or a region at which the pixel electrode 18 and the light emittinglayer 122 are brought into contact with each other) and an effect ofcollecting the propagated light can be provided. In this way, there canbe provided the light emitting display device increasing the efficiencyof taking out the generated light to outside without particularlyincreasing the number of process, achieving bright image display by lowpower consumption and achieving bright image display withoutdeteriorating reliability.

[Embodiment 2]

According to the embodiment, an explanation will be given of an examplein which a shape of an opening portion provided at the light emittingregion is different from that of Embodiment 1. An explanation will begiven in reference to FIGS. 5A and 5B and FIGS. 6A and 6B, notations areprovided only for constitutions different from those of Embodiment 1 andnotations the same as those of Embodiment 1 are used for other portions.

In FIG. 5A, constitutions different from those of Embodiment 1 are apixel electrode 501 and an opening portion 502. The opening portion 502is an example of constituting a shape of the opening portion by acircular shape and providing the opening portion irregularly at insideof the light emitting region. Further, it is not necessarily needed toprovide the opening portions 502 irregularly but the opening portions502 can also be aligned regularly.

FIGS. 6A and 6B are drawings in correspondence with sectional viewsconstituted by cutting a top view shown in FIG. 5A by lines B-B′ andC-C′. Further, since a drawing in correspondence with a sectional viewconstituted by cutting FIG. 5A by a line A-A′ is the same as FIG. 3A andtherefore, an explanation thereof will be omitted here. As shown byFIGS. 6A and 6B, a curved face is formed at a surface of the pixelelectrode 501 by the opening portion 502, as a result, light(particularly, propagated light) emitted from the light emitting layer122 is emitted to the lower side at the curved face portion of the pixelelectrode 501 and promotion of the efficiency of taking out light tooutside is achieved.

As described above, by embodying the invention by the constitution shownin the embodiment, a surface of the pixel electrode 501 can beconstituted by the curved face at the light emitting region at inside ofthe pixel and an effect of collecting propagated light can be provided.In this way, there can be provided the light emitting display devicecapable of promoting the efficiency of taking out the generated light tooutside without particularly increasing the number of process, achievingbright image display by low power consumption and achieving bright imagedisplay without deteriorating reliability.

[Embodiment 3]

According to the embodiment, an explanation will be given of an examplein which a shape of an opening portion provided at the light emittingregion is different from that of Embodiment 1. An explanation will begiven in reference to FIGS. 7A and 7B and FIGS. 8A and 8B, notations areprovided only for constitutions different from those of Embodiment 1 andnotations the same as those of Embodiment 1 are used for other portions.

In FIG. 7A, constitutions different from those of Embodiment 1 are apixel electrode 701 and an opening portion 702. The opening portion 702is an example of constituting a shape of the opening portion by alattice shape and providing a plurality of lattices to arrange regularlyin a light emitting region. Further, it is not necessarily needed thatthe plurality of lattices are arranged regularly but a size of anindividual lattice may be irregular.

FIGS. 8A and 8B are drawings in correspondence with sectional viewsconstituted by cutting a top view shown in FIG. 7A by lines B-B′ andC-C′. Further, a drawing correspondent to a sectional view constitutedby cutting the top view by a line A-A′ is the same as FIG. 3A andtherefore, an explanation thereof will be omitted here. As shown byFIGS. 8A and 8B, a curved face is formed at a surface of the pixelelectrode 701 by the opening portion 702, as a result, light(particularly, propagated light) emitted from the light emitting layer122 is emitted to the lower side by the curved face portion of the pixelelectrode 701 and promotion of the efficiency of taking out light tooutside is achieved.

As described above, by embodying the invention by the constitution shownin the embodiment, the surface of the pixel electrode 701 can beconstituted by the curved face at the light emitting region in the pixeland an effect of collecting the propagated light can be provided. Inthis way, there can be provided the light emitting display devicecapable of promoting the efficiently of taking out the generated lightto outside without particularly increasing the number of process,achieving bright image display by low power consumption and achievingbright image display without deteriorating reliability.

[Embodiment 4]

According to the embodiment, an explanation will be given of an exampleof covering the surface of the flattening film 112 (also including theside surface of the opening portion 19) by an inorganic insulating filmin Embodiment 1. An explanation will be given in reference to FIGS. 9A,9B and 9C, notations are provided only for constitutions different fromthose of Embodiment 1 and notations used in Embodiment 1 are used forother portions pertinently as necessary.

FIGS. 9A through 9C are drawings respectively in correspondence withFIGS. 3A through 3C. In FIG. 9A, the surface of the flattening film 112is covered by a barrier film 901. The barrier film 901 is provided afterforming the opening portion 19 and therefore, formed to cover the sidesurface of the opening portion 19. Further, at a portion in contact witha transistor, in forming the first contact portion, the barrier film 901is also etched to perforate. At this occasion, as shown by FIG. 9C, itis not particularly necessary to etch the barrier film 901 at a bottomface of the opening portion 19.

The constitution of the embodiment is effective in using an insulatingfilm formed by a method of coating a solution (so-to-speak spin coatingmethod) particularly as the flattening film 112. The constitution iseffective when a resin film of, s representatively, a polyimide film, anacrylic resin film or the like is used as the flattening film and aneffect thereof is restraining degassing from the flattening film 112.

In a related art, in the case of the insulating film formed by the spincoating method, although a solvent dissolved with a material for forminga film is coated by the spin coating method and the material is sinteredto form a thin film. Although extra solvent is volatized in sintering,there is a case in which such a solvent remains in the film or moistureis adsorbed after forming the film. Therefore, after finishing thedevice, degassing is caused from inside of the film by heating todeteriorate an organic compound constituting the light emitting layer.

However, according to the constitution of the embodiment, degassing fromthe flattening film 112 can be restrained by the barrier film 901 andtherefore, a degassed component dose not reach the light emitting layerprovided over the flattening film 112 and a highly reliable displaydevice which is not deteriorated can be provided even after finishingthe light emitting display device. Further, it is also effective toprevent the degassed component from diffusing to the side of thetransistor by providing the same barrier film blow the flattening film112.

As the barrier film 901, a thin film having a blocking effect againstoxygen and moisture can be used and a silicon nitride film, a siliconnitroxide film, an aluminum oxide film, an aluminum nitroxide film or adiamond-like carbon film can be used therefor. Further, in forming thebarrier film 901, it is preferable to form the film by using asputtering method in order to minimize degassing from being broughtabout from the flattening film 112.

By embodying the invention by the constitution shown in the embodiment,reliability of the light emitting display device can particularly bepromoted. Naturally, the embodiment can be embodied by combining withany constitution of Embodiments 1 through 3.

[Embodiment 5]

According to the embodiment, an explanation will be given of a positionof forming an insulating film (correspondent to the insulating film 121in Embodiment 1) for partitioning the light emitting region in referenceto FIGS. 10A and 10B. In FIG. 10A, numeral 1001 designates a flatteningfilm and FIG. 10A is a sectional view precisely cutting an openingportion. Numeral 1002 designates a silicon nitride film functioning as abarrier film, numeral 1003 designates a pixel electrode and numeral 1004designates an insulating film for partitioning the light emittingregion.

In the case of FIG. 10A, an end portion of the insulating film 1004 ispatterned to be contained in the opening portion. When such aconstitution is constructed, luminescence is not caused in a region 1005surrounded by a dotted line in the drawing and therefore, lightadvancing to an outer side of the light emitting region can be reduced.Although the light advancing to the outer side of the light emittingregion contributes to an increase in the brightness, the light also dimsa contour of a pixel and therefore, it is preferable to construct theconstitution as shown by FIG. 10A in the case of achieving highly fineimage quality.

Further, in the case of FIG. 10B, an insulating film 1006 is provided toconceal a bottom face of an opening portion and only a portion of a sidesurface is exposed. When such a constitution is constructed,luminescence is not caused in a region 1007 surrounded by a dotted linein the drawing. This is because when the light emitting layer does notexcellently rides over an end portion of the flattening film 1001 (aportion of thickening a film thickness) there is a concern of making adeterioration progress from the portion and therefore, the region isconstructed by a constitution which is not used as a light emittingregion. Actually, when the radius of curvature of the side surface ofthe opening portion provided at the flattening film 1001 is large, aproblem is not particularly posed, however, when the radius of curvatureis small, such a constitution is effective as a constitution ofpromoting reliability. Naturally, also light progressing to the outerside of the light emitting region can also be restrained similar to FIG.10A and therefore, an advantage of achieving highly fine image qualityis also provided.

As described above, by embodying the invention by the constitution shownin the embodiment, promotion of the image quality of the light emittingdisplay device can be achieved and also reliability can be promoted.Naturally, the embodiment can be embodied also by combining with anyconstitution of Embodiments 1 through 4.

[Embodiment 6]

Structures of the thin film transistors described in Embodiments 1though 5 are top gate type (more specifically, planer structure),respectively. However, the present invention is not limited to thereof,and a bottom gate structure (more specifically, inversed staggerstructure) can be applied to thin film transistors in each embodiment.Further, the present invention is not necessarily limited to a thin filmtransistor, and may be applied to a transistor having a MOS structurethat is formed by using a silicon well.

[Embodiment 7]

In this embodiment, a structure of the entire light emitting displaydevice that can apply the present invention will be described withreference to FIGS. 11A and 11C. FIG. 11A is a top view of a lightemitting display device produced by sealing an element substrate inwhich thin film transistors are formed with a sealing material. FIG. 11Bis a cross sectional view along a line B-B′ in FIG. 11A. FIG. 11C is across sectional view along a line A-A′ in FIG. 11A.

A pixel portion (display portion) 22, a data line driver circuit 23,gate line driver circuits 24 a and 24 b, and a protective circuit 25,which are provided so as to surround the pixel portion 22, are locatedon a substrate 21, and a seal material 26 is provided to surround them.The structure of the pixel portion 22 preferably refers to Embodiments 1to 4 and its description. As the seal material 26, a glass material, ametallic material (typically, a stainless material), a ceramic material,or a plastic material (including a plastic film) can be used. As shownin Embodiments 1 to 4, it can be also sealed with only an insulatingfilm. In addition, it is necessary to use a translucent materialaccording to a radiation direction of light from a light emittingelement.

The seal material 26 may be provided to partially overlap with the dataline driver circuit 23, the gate line driver circuits 24 a and 24 b, andthe protective circuit 25. A cover material 27 is provided using theseal material 26, so that an airtight space 28 is produced by thesubstrate 21, the seal material 26, and the cover material 27. Ahygroscopic agent (barium oxide, calcium oxide, or the like) 29 isprovided in advance in a concave portion of the cover material 27, sothat it has a function of absorbing moisture, oxygen, and the like tokeep an atmosphere clean in a portion of the above airtight space 28,thereby suppressing the deterioration of a light emitting layer. Theconcave portion is covered with a cover material 30 with a fine meshshape. The cover material 30 allows air and moisture to passtherethrough but not the hygroscopic agent 29. Note that the airtightspace 28 is preferably filled with a noble gas such as nitrogen orargon, and can be also filled with a resin or a liquid if it is inert.

Also, an input terminal portion 31 for transmitting signals to the dataline driver circuit 23 and the gate line driver circuits 24 a and 24 bis provided on the substrate 21. Data signals such as video signals aretransferred to the input terminal portion 31 through a FPC (flexibleprinted circuit) 32. With respect to a cross section of the inputterminal portion 31, as shown in FIG. 11B, an input wiring having astructure in which an oxide conductive film 34 is laminated on a wiring33 formed together with a gate wiring or a data wiring is electricallyconnected with a wiring 35 provided in the FPC 32 side through a resin37 to which conductors 36 are dispersed. Note that a spherical polymercompound for which plating processing using gold or silver is conductedis preferably used for the conductors 36.

Also, an enlarged view of a region 38 surrounded by a dotted line inFIG. 11C is shown in FIG. 11D. The protective circuit 25 is preferablycomposed by combining a thin film transistor 39 and a capacitor 40, andany known structure may be used therefor. The present invention has sucha feature that the formation of the capacitor is possible withoutincreasing the number of photolithography steps together with theimprovement of contact holes. In this embodiment, the capacitor 40 isformed utilizing the feature. Note that the structure of the thin filmtransistor 39 and that of the capacitor 40 can be understood ifEmbodiment 1 and description thereof are referred to, and therefore thedescription is omitted here.

In this embodiment, the protective circuit 25 is provided between theinput terminal portion 31 and the data line driver circuit 23. When anelectrostatic signal such as an unexpected pulse signal is inputtedtherebetween, the protective circuit releases the pulse signal to theoutside. At this time, first, a high voltage signal which isinstantaneously inputted can be dulled by the capacitor 40, and otherhigh voltages can be released to the outside through a circuit composedof a thin film transistor and a thin film diode. Of course, theprotective circuit may be provided in other location, for example, alocation between the pixel portion 22 and the data line driver circuit23 or locations between the pixel portion 22 and the gate line drivercircuits 24 a and 24 b.

As described above, according to this embodiment, when the presentinvention is carried out, an example in which the capacitor used for theprotective circuit for electrostatic countermeasures and the like whichis provided in the input terminal portion is simultaneously formed isindicated. This embodiment can be carried out by being combined with anystructure of Embodiments 1 to 6.

[Embodiment 8]

Examples of electronics employing a light emitting display device of thepresent invention to a display portion are: a video camera; a digitalcamera; a goggle type display (head mounted display); a navigationsystem; an audio reproducing apparatus (car audio, an audio component,and the like); a laptop computer; a game machine; a portable informationterminal (a mobile computer, a cellular phone, a portable game machine,an electronic book, etc.); and an image reproducing apparatus includinga recording medium (specifically, an appliance capable of processingdata in a recording medium such as a Digital Versatile Disk (DVD) andhaving a display apparatus that can display the image of the data).Specific examples of the electronics are shown in FIGS. 12A to 12H.

FIG. 12A shows a television, which comprises a casing 2001, a supportingbase 2002, a display portion 2003, speaker portions 2004, a video inputterminal 2005, etc. The present invention is applied to the displayportion 2003. The term television includes every television fordisplaying information such as one for a personal computer, one forreceiving TV broadcasting, and one for advertisement.

FIG. 12B shows a digital camera, which comprises a main body 2101, adisplay portion 2102, an image receiving portion 2103, operation keys2104, an external connection port 2105, a shutter 2106, etc. The presentinvention is applied to the display portion 2102.

FIG. 12C shows a laptop computer, which comprises a main body 2201, acasing 2202, a display portion 2203, a keyboard 2204, an externalconnection port 2205, a pointing mouse 2206, etc. The present inventionis applied to the display portion 2203.

FIG. 12D shows a mobile computer, which comprises a main body 2301, adisplay portion 2302, a switch 2303, operation keys 2304, an infraredray port 2305, etc. The present invention is applied to the displayportion 2302.

FIG. 12E shows a portable image reproducing apparatus equipped with arecording medium (a DVD player, to be specific). The apparatus comprisesa main body 2401, a casing 2402, a display portion A 2403, a displayportion B 2404, a recording medium (such as DVD) reading portion 2405,operation keys 2406, speaker portions 2407, etc. The display portion A2403 mainly displays image information whereas the display portion B2404 mainly displays text information. The present invention is appliedto the display portions A 2403 and B 2404. The term image reproducingapparatus equipped with a recording medium includes domestic gamemachines.

FIG. 12F shows a goggle type display (head mounted display), whichcomprises a main body 2501, display portions 2502, and arm portions2503. The present invention is applied to the display portion 2502.

FIG. 12G shows a video camera, which comprises a main body 2601, adisplay portion 2602, a casing 2603, an external connection port 2604, aremote control receiving portion 2605, an image receiving portion 2606,a battery 2607, an audio input portion 2608, operation keys 2609, etc.The present invention is applied to the display portion 2602.

FIG. 12H shows a cellular phone, which comprises a main body 2701, acasing 2702, a display portion 2703, an audio input portion 2704, anaudio output portion 2705, operation keys 2706, an external connectionport 2707, an antenna 2708, etc. The present invention is applied to thedisplay portion 2703. If the display portion 2703 displays whitecharacters on a black background, power consumption of the cellularphone can be reduced.

As described above, the display apparatus obtained by applying thepresent invention may be used as the display portions of everyelectronics. Also, the electronics of the present Embodiment may use anyconstitutions of the light emitting display device shown in Embodiments1 to 7.

According to the invention, a direction of advancing propagated lightpropagated at inside of a light emitting layer can be corrected to alower direction by providing a curved face at a surface of a pixelelectrode in a light emitting region to thereby promote an efficiency oftaking out light to outside. Further, the surface of the pixel electrodecan be constituted by the curved face by only providing an opening at aninsulating film therebelow and an increase in the number of processes isnot particularly brought about. As a result, there can be provided alight emitting device capable of achieving bright image display by lowpower consumption by promoting the efficiency of taking out light tooutside and achieving light image display without deterioratingreliability.

1. A light emitting device comprising: a plurality of pixels providedwith light emitting elements; and a thin film transistor and a pixelelectrode electrically connected to the thin film transistor provided ateach of the plurality of pixels, wherein an insulating film is providedover the thin film transistor and the pixel electrode is provided overthe insulating film, wherein the insulating film includes an openingportion, a side surface of which is curved at a light emitting region,and wherein each of the light emitting elements comprises the pixelelectrode, a light emitting layer, and an opposed electrode.
 2. Thelight emitting device according to claim 1, wherein the pixel electrodecomprises an oxide conductive film.
 3. The light emitting deviceaccording to claim 1, wherein the insulating film is a photosensitiveresin film.
 4. The light emitting device according to claim 1, whereinthe opening portion has a shape of a groove.
 5. The light emittingdevice according to claim 1, wherein the opening portion has a circularshape.
 6. The light emitting device according to claim 1, wherein theopening portion has a shape of a lattice.
 7. A light emitting deviceaccording to claim 1, wherein the light emitting layer comprises anorganic compound.
 8. A light emitting device comprising: a plurality ofpixels provided with light emitting elements; and a thin film transistorand a pixel electrode electrically connected to the thin film transistorprovided at each of the plurality of pixels, wherein an insulating filmis provided over the thin film transistor and the pixel electrode isprovided over the insulating film, wherein the insulating film includesan opening portion a side surface of which is curved at a light emittingregion and the pixel electrode covers, a side surface of the openingportion, and wherein each of the light emitting elements comprises thepixel electrode, a light emitting layer, and an opposed electrode. 9.The light emitting device according to claim 8, wherein the pixelelectrode comprises an oxide conductive film.
 10. The light emittingdevice according to claim 8, wherein the insulating film is aphotosensitive resin film.
 11. The light emitting device according toclaim 8, wherein the opening portion has a shape of a groove.
 12. Thelight emitting device according to claim 8, wherein the opening portionhas a circular shape.
 13. The light emitting device according to claim8, wherein the opening portion has a shape of a lattice.
 14. A lightemitting device according to claim 8, wherein the light emitting layercomprises an organic compound.
 15. A light emitting device comprising: aplurality of pixels provided with light emitting elements; and a thinfilm transistor and a pixel electrode electrically connected to the thinfilm transistor provided at each of the plurality of pixels; wherein aninsulating film is provided over the thin film transistor and the pixelelectrode is provided over the insulating film, wherein the insulatingfilm includes an opening portion, a side surface of which is curved at alight emitting region and a surface of the pixel electrode includes acurved face along a shape of the opening portion, and wherein each ofthe light emitting elements comprises the pixel electrode, a lightemitting layer, and an opposed electrode.
 16. The light emitting deviceaccording to claim 15, wherein the pixel electrode comprises an oxideconductive film.
 17. The light emitting device according to claim 15,wherein the insulating film is a photosensitive resin film.
 18. Thelight emitting device according to claim 15, wherein the opening portionhas a shape of a groove.
 19. The light emitting device according toclaim 15, wherein the opening portion has a circular shape.
 20. Thelight emitting device according to claim 15, wherein the opening portionhas a shape of a lattice.
 21. A light emitting device according to claim15, wherein the light emitting layer comprises an organic compound. 22.A light emitting device comprising: a plurality of pixels comprising aplurality of thin film transistors, a plurality of pixel electrodes, anda plurality of light emitting elements; and a insulating film formedover the plurality of thin film transistors, wherein the plurality ofpixel electrodes are formed over the insulating film, wherein theinsulating film has at least one opening portion in each of theplurality of the pixels, wherein the opening portion has a curved sidesurface at a light emitting region, and wherein each of the lightemitting elements comprises the pixel electrode, a light emitting layer,and an opposed electrode.
 23. A light emitting device according to claim22, wherein the pixel electrode covers a surface of the opening portionand the insulating film.
 24. A light emitting device according to claim22, wherein the light emitting layer comprises an organic compound. 25.A light emitting device comprising: a plurality of pixels, each of whichcomprises a thin film transistor, a pixel electrode electricallyconnected to the thin film transistor, and a light emitting elementhaving the pixel electrode, a light emitting layer, and an opposedelectrode over the thin film transistor, wherein at least one islandshaped insulating layer is formed in each of the plurality of pixels,wherein the pixel electrode is formed over the island shaped insulatinglayer, wherein the island shaped insulating layer has at least oneopening portion and the opening portion has a curved side surface.
 26. Alight emitting device according to claim 25, wherein the device furthercomprises a data wiring, and the opening portion is formed along withthe data wiring.
 27. A light emitting device according to claim 25,wherein the pixel electrode covers a surface of the island shapedinsulating layer and the opening portion.
 28. A light emitting deviceaccording to claim 25, wherein the light emitting layer comprises anorganic compound.